Handle NULL header in doHeaderUnload()

- avoids having to separately check elsewhere and avoids segfaulting
  on headerUnload() and headerReload() on NULL headers

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/header.c b/lib/header.c
index 45bbc2dd8..c4cc78e06 100644
--- a/lib/header.c
+++ b/lib/header.c
@@ -456,6 +456,8 @@ static void * doHeaderUnload(Header h,
     int i;
     int drlen, ndribbles;
 
+    if (h == NULL) return NULL;
+
     /* Sort entries by (offset,tag). */
     headerUnsort(h);
 
@@ -1013,8 +1015,6 @@ int headerWrite(FD_t fd, Header h, enum hMagic magicp)
     size_t length;
     void * uh;
 
-    if (h == NULL)
-	return 1;
     uh = doHeaderUnload(h, &length);
     if (uh == NULL)
 	return 1;